US4006979A - Electromagnetic release device for a motion picture camera - Google Patents

Electromagnetic release device for a motion picture camera Download PDF

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Publication number
US4006979A
US4006979A US05/432,247 US43224774A US4006979A US 4006979 A US4006979 A US 4006979A US 43224774 A US43224774 A US 43224774A US 4006979 A US4006979 A US 4006979A
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United States
Prior art keywords
circuit
electromagnet
motor
shutter
blocking
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Expired - Lifetime
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US05/432,247
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English (en)
Inventor
Teiji Hashimoto
Tomoshi Takigawa
Toshikazu Ichiyanagi
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Canon Inc
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Canon Inc
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Publication date
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B17/00—Details of cameras or camera bodies; Accessories therefor
    • G03B17/38—Releasing-devices separate from shutter

Definitions

  • This invention relates to an electromagnetic release device for a motion picture camera, and more particularly to such a device which ensures the shutter of the camera to be stopped at a predetermined position when depression of a camera's shutter release member is released to cut off the power supply to a shutter drive motor.
  • an electromagnetic release device for a motion picture camera has been designed such that when depression of the shutter release member is released, a power supply circuit to the shutter drive motor is opened and at the same time, a shutter stop member is driven by electromagnetic means for engagement with a shutter blade shaft driven by the shutter drive motor to thereby block the rotation of the shutter blade shaft and stop the shutter at a predetermined position.
  • the shutter drive motor continues to revolve only from its own inertia force after the power supply circuit to the shutter drive motor has been opened, and this has often prevented the shutter blade shaft from being rotated fully to its predetermined rest position, with a result that the shutter is stopped while being still left open.
  • FIG. 1 diagrammatically shows an embodiment of the electric circuit which is applicable to the electromagnetic release device for a motion picture camera according to the present invention.
  • FIG. 2 diagrammatically shows another embodiment of the electric circuit which is applicable to the electromagnetic release device for a motion picture camera according to the present invention.
  • FIG. 3 diagrammatically shows still another embodiment of the electric circuit which is applicable to the electromagnetic release device for a motion picture camera according to the present invention.
  • FIG. 4 diagrammatically shows a further embodiment of the electric circuit which is applicable to the electromagnetic release device for a motion picture camera according to the present invention.
  • FIG. 5 is a front view showing the mechanical construction of the shutter stop mechanism in the electromagnetic release device for a motion picture camera according to the present invention.
  • FIG. 6 is a plan view taken in the direction of arrow II in FIG. 5.
  • FIG. 7 is a right-hand side view taken in the direction of arrow III in FIG. 5.
  • FIG. 8 is a vertical cross-section taken along line IV--IV in FIG. 7.
  • an electromagnetic release device for a motion picture camera essentially comprises first switching means for closing and opening a drive circuit for electromagnetic means, second switching means for closing and opening a power supply circuit to a shutter drive motor for rotating a shutter blade shaft, delay means connected between said first and said second switching means, and a stop mechanism provided with a stop member actuated by the electromagnetic force of said electromagnetic means for stopping the rotation of the shutter blade shaft at a predetermined rest position, whereby supply and cut-off of the power to the second switching means may be delayed by the delay means for a predetermined time with respect to the operation of the first switching means.
  • a shutter stop mechanism applicable to the electromagnetic release device for a motion picture camera according to the present invention.
  • a yoke 1 has a spring-engaging pin 5 studded therein and is mounted to the camera body by means of screws 13.
  • the yoke 1 holds an electromagnet 4 with an iron core 4a as its axis.
  • a crank-like armature 3 is loosely received for rocking movement in a slot 1a formed through the yoke 1 and comprises a stop portion 3b, an intermediate portion 3c and an end portion 3d.
  • the intermediate portion 3c is provided with a spacer 3a.
  • a spring 6 is secured at one end to the spring-engaging pin 5 and at the other end to a spring-engaging hole 3d formed in the end of the armature 3, and normally biases the armature 3 for counter-clockwise rotation about the slot 1a of the yoke 1.
  • a shaft 8 for rotating a shutter blade (not shown) has mounted thereon a gear 9 rotatable with the shutter blade at a speed ratio of 1:1, and a stop member having a stop cam 10 formed integrally therewith and engageable with the stop portion 3b when the shutter is stopped.
  • a switch S3 is provided and adapted to be closed during engagement between stop portion 3b and the stop cam 10 and to be opened during such engagement.
  • the stop mechanism so constructed is applicable to any of some embodiments of electric circuit which will hereinafter be described.
  • FIG. 1 shows an embodiment of the electric circuit which is applicable to the electromagnetic release device for a motion picture camera according to the present invention.
  • the above-described shutter stop mechanism is controlled by such circuit.
  • the circuit shown includes a release switch S1 constituting first switching means, a main switch S2, an exciting coil L1 for exciting the aforesaid electromagnet 4, a capacitor C1 constituting delay means, resistors R1 and R2, a shutter drive motor M1, a transistor Tr1 constituting second switching means for switching on and off the power supply circuit to the motor M1, and a power source E1.
  • the closing of the main switch S2 and of the release switch S1 has initially caused the capacitor C1 to be charged and therefore, when this occurs, the transistor Tr1 is in OFF state to maintain the motor M1 unenergized, but since the capacitor C1 in use is selected such that it is completely charged by the time when the disengagement of the stop portion 3b from the stop cam 10 occurs, the disengagement between the stop portion 3b and the stop cam 10 is immediately followed by turn-on of the transistor Tr1, which thus connects power supply to the shutter drive motor M1 which in turn drives the shutter shaft 8 for rotation. Thus, picture-taking is started.
  • the transistor Tr1 remains in its ON state for a predetermined time until the current stored in the capacitor C1 has been discharged therefrom, so that the motor M1 still continues to revolve. Only after the stop cam 10 is engaged by the stop portion 3b of the armature 3 which has moved into the path of rotation of the stop cam 10, the discharge of the capacitor C1 is completed to turn off the transistor Tr1 and cut off the power supply to the drive motor M1, whereupon the motor is deenergized.
  • deenergization of the drive motor M1 occurs only after the engagement between the stop cam 10 and the stop portion 3b of the armature 3 has taken place at a predetermined position, and this ensures the shutter to be stopped at a predetermined position.
  • FIG. 2 shows an embodiment improved over that of FIG. 1.
  • a relay switch S3 is inserted behind the transistor Tr1 in the electric circuit of FIG. 1 so as to prevent any power loss from occurring between the emitter and collector of the transistor in the circuit of FIG. 1.
  • similar reference characters designate elements which are similar in function and operation to those shown in FIG. 1.
  • FIG. 3 there is shown a further embodiment which is additionally provided with a circuit for changing over the electromagnetic release device of the present invention between single-frame photography and continuous photography and a circuit for limiting the holding current of the electromagnet 4 during picture-taking.
  • M1 is the shutter drive motor
  • S5 is a change-over switch for changing over the direction of revolution of the motor M1
  • Tr1 is a transistor as the second switching means for closing and opening the power supply circuit to the motor M1
  • S1 and S2 designate a release switch and a main switch, respectively
  • R1 and R2 are resistors
  • C1 is a capacitor which is delay means.
  • Tr2 is a transistor as the first switching means for closing and opening the drive circuit for the electromagnet 4;
  • R7 is a resistor connected to the base of the transistor Tr2;
  • L1 is a drive coil;
  • R3 is a resistor;
  • S3 is a normally closed switch mechanically actuated by the electromagnet 4 adapted to be opened only when the electromagnet 4 is substantially in its operated position;
  • the portion encircled by dotted line A is a circuit so designed as to limit the current during picture-taking, i.e.
  • Tr3 is a transistor; R4, R5 and R6 are resistors; C2 is a capacitor which is a delay means; S4 is a manually operated switch which is to be opened for single-frame photography and closed for continuous photography; and the portion encircled by dotted line B is a circuit so designed as to change over the operation mode between single-frame photography and continuous photography. This circuit serves to turn on the transistor Tr3 when the switch S4 is in its OFF position, i.e. for a period of time required to advance the film by one frame during single-frame photography.
  • the switch S4 is opened and two main and release switches S2 and S1 closed to effect single-frame photography
  • the picture-taking is started in the same process as described with respect to the continuous photography.
  • the capacitor C2 continues to be charged through the resistor R4 and R5 even if the release switch S1 is continuedly closed, so that the transistor Tr3 is turned off only after the film has been advanced by one frame.
  • the transistor Tr2 is also turned off to stop the shutter at its predetermined position as described previously, thus terminating the single-frame photography.
  • FIG. 4 shows a further embodiment of the electromagnetic release device according to the present invention which again is additionally provided with a circuit for changing over the operation mode between single-frame photography and continuous photography and a circuit for limiting the holding current of the electromagnet 4 during picture-taking.
  • M1 is a shutter drive motor
  • S5 is a change-over switch for changing over the direction of revolution of the motor M1
  • Tr1 is a transistor as the second switching means for closing and opening the power supply circuit to the motor M1
  • S1 and S2 are a release and a main switch, respectively
  • R4 and R9 are resistors
  • C1 is a capacitor which is delay means. These constitute a delay circuit.
  • L1 and L2 are exciting coils for exciting the electromagnet 4 shown in FIGS. 5-8;
  • Tr2 is a transistor as the first switching means for energizing and deenergizing the exciting coil L1;
  • R7 is a resistor connected to the base of the transistor Tr2; and
  • S4 is a manually operated switch which is to be opened for single-frame photography and closed for continuous photography.
  • the electromagnet 4 rocks the armature 3 in the direction of arrow A against the force of the spring 6, so that the stop portion 3b, of the armature 3 is retracted out of the path of rotation of the stop cam 10, thus unlocking the shutter stop mechanism in the same manner as described with respect to the embodiment of FIG. 1 (see FIG. 8).
  • the capacitor C2 has been completely charged to turn off the transistor Tr2 and cut off the power supply to the exciting coil L1, which is thus deenergized.
  • the transistor Tr1 is turned on after unlocking of the stop mechanism by the action of the capacitor C1, as noted above with respect to the embodiment of FIG. 1.
  • the shutter drive motor M1 is energized to drive the unshown shutter blade, thus starting the continuous photography.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Shutters For Cameras (AREA)
US05/432,247 1973-01-17 1974-01-10 Electromagnetic release device for a motion picture camera Expired - Lifetime US4006979A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JA48-7670 1973-01-17
JP48007670A JPS5838779B2 (ja) 1973-01-17 1973-01-17 シネカメラ ノ シヤツタデンジカイジヨソウチ

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US4006979A true US4006979A (en) 1977-02-08

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US05/432,247 Expired - Lifetime US4006979A (en) 1973-01-17 1974-01-10 Electromagnetic release device for a motion picture camera

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JP (1) JPS5838779B2 (enrdf_load_stackoverflow)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5650501Y2 (enrdf_load_stackoverflow) * 1975-02-05 1981-11-26

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3601481A (en) * 1968-12-23 1971-08-24 Leitz Ernst Gmbh Shutter release device for motion picture cameras
US3602584A (en) * 1968-07-12 1971-08-31 Niezoldi & Kraemer Gmbh Electromagnetic release arrangement for motion picture cameras
US3603678A (en) * 1968-01-13 1971-09-07 Niezoldi & Kraemer Gmbh Motion-picture camera
US3790264A (en) * 1971-07-07 1974-02-05 Bosch Photokino Gmbh Movie camera release control circuit with voltage stabilization

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3603678A (en) * 1968-01-13 1971-09-07 Niezoldi & Kraemer Gmbh Motion-picture camera
US3602584A (en) * 1968-07-12 1971-08-31 Niezoldi & Kraemer Gmbh Electromagnetic release arrangement for motion picture cameras
US3601481A (en) * 1968-12-23 1971-08-24 Leitz Ernst Gmbh Shutter release device for motion picture cameras
US3790264A (en) * 1971-07-07 1974-02-05 Bosch Photokino Gmbh Movie camera release control circuit with voltage stabilization

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JPS5838779B2 (ja) 1983-08-25
JPS4996729A (enrdf_load_stackoverflow) 1974-09-12

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